The present invention relates to a tape tightening mechanism for an automatic packer which can be easily manufactured for accurate and convenient operation by users.
When using an automatic packer, a tape for binding the package must be sent into a tape rail located at an upper part of the packer. The tape in the tape rail is then pulled backward in order to tighten around the package. This is the first backward pulling of the tape. Another backward pulling of the tape with stronger force is needed to further tighten the package before the tape can be molten and cut to complete the packing. The automatic packer includes a tape-operating unit for feeding and backward pulling the tape.
Most of the automatic packers available in the markets have a tape-operating unit capable of feeding tape and performing first and second backward pulling of tape to pack a package. Such tape-operating unit performs the first backward pulling of tape by a rotatable rear wheel which rotates at slow speed and has small driving force and therefore the packing operation is inefficient and the tape can not be well tightened around the package. For packages that need to be highly tightened, such type of automatic packer is not suitable at all.
Moreover, the automatic packer is provided with a tension arm to perform the second backward pulling of tape to further tighten the tape around the package. As shown in FIG. 1, the tension arm 10 is swung backward by a rotating cam 11 to pull the tape backward. The tension arm 10 has a front end contacting with a rear end of the tape-operating unit 12 and a rear end connected to a curved rail 13 which houses a fixed curved rail 14 having the same radius of curvature as that of the curved rail 13. When the tension arm 10 swings forth and back about a shaft thereof, the curved rail 13 connected to its rear end moves at the same time but remains in a state of housing the fixed curved rail 14. That is, when the tension arm 10 swings backward to perform the second backward pulling of tape, the backward pulled tape would be partially sent back into a tape storage (not shown) via the partially telescoped curved rails 13 and 14. Such mechanism for the tension arm 10 to perform the second backward pulling of tape enables better tightening of the package. However, it is very important the two curved rails 13 and 14 are manufactured with highly accurate curvature to enable successful second backward pulling of tape. Therefore, such tape tightening mechanism is difficult to manufacture and requires higher manufacturing cost. Furthermore, there are many limitations in the installation of such tape tightening mechanism to ensure good housing of the curved rail 13 around the curved rail 14 when the tension arm 10 swings.
It is therefore tried by the inventor to develop an improved tape tightening mechanism for an automatic packer to eliminate the drawbacks found in the conventional tape-tightening mechanism for second backward pulling of tape.